1. Field of the Invention
This invention relates to fuels for internal combustion engines and more particularly to the provision of a novel additive for such fuels.
As is well known, hydrocarbon fuels have a tendency to form polymeric materials (variously called "gum" or "sludge" or "varnish") in various parts of fuel systems. These resin-like deposits tend to form in the fuel supply lines, fuel filter, carburetor, fuel control injectors, intake manifold and valve stems. Such deposits are objectionable not only because of their effect on mechanical performance but also because they decrease the breathing efficiency in engines of the spark ignition type.
Although each type of fuel is composed essentially of hydrocarbons their stability characteristics differ considerably. Thus, typical automotive fuels contain straight and branched chain compounds while aircraft fuels contain a smaller proportion of olefins. Currently, certain types of fuels contain increased amounts of cracked stocks resulting in a higher olefin content and increased susceptibility to the formation of gum.
2. Background of the Invention
The field of this invention evidences considerable research interest. U.S. Pat. No. 3,415,750; Great Britain Pat. No. 1,162,436; U.S. Pat. No. 3,873,460 and coassigned U.S. Pat. Nos. 4,048,080; 4,266,944; and 4,321,062 disclose various classes of chemicals having utility detergents or dispersants in lubricating oil compositions.
The compounds used herein as carburetor detergents are disclosed and claimed in co-pending application Ser. No. 495,295, filed May 16, 1983. Said application is incorporated herein by reference.